1. Field of the Invention
The present invention relates to a machine for delivering ballast to a track and for tamping the ballast, which comprises a machine frame supported on the track by undercarriages for movement in an operating direction and mounted on the machine frame a ballast tamping unit, a track lifting and lining unit, a ballast storage bin having outlet means for delivering ballast from the bin to the track, a ballast conveyor means having an output end above the ballast storage bin and an input end, and a vertically adjustable broom arrangement for sweeping excess ballast from the track to the ballast conveyor means input end.
2. Description of the Prior Art
A machine of this general type has been disclosed in U.S. Pat. No. 4,770,104, this machine being comprised of a ballast cleaning machine preceding a ballast tamping machine. The machine frame of the ballast tamping machine carries a ballast tamping unit and a ballast lifting and lining unit which is preceded, in the operating direction, by a ballast storage bin having outlet means for delivering ballast to the track and receiving cleaned ballast from an output end of a ballast conveyor means arranged above the bin. A vertically adjustable broom arrangement sweeps excess ballast to the lower input end of the ballast conveyor means. Since the ballast is discharged through the outlet means of the ballast storage bin while the ballast tamping machine advances continuously, it is relatively difficult to limit the discharge of the ballast into the cribs of the track.
U.S. Pat. No. 4,257,331 discloses a machine for cleaning the ballast and then to compact the cleaned ballast. This machine comprises a ballast cleaning machine preceding a ballast compacting machine coupled to the ballast cleaning machine. A ballast storage bin having outlet means for delivering the cleaned ballast to the track is positioned at the front end of the ballast compacting machine, and a ballast conveyor band conveys the cleaned ballast from the ballast cleaning machine to the bin. A vertically adjustable broom arrangement is mounted rearwardly of the ballast compacting unit. This machine serves for compacting the cleaned ballast immediately after it has been delivered to the track.